Synthesis and antitumor activity evaluation of a novel series of xanthone derivatives.

A natural xanthone, 1,3,6-trihydroxy-5-methoxyxanthone, was totally synthesized for the first time by six steps in 31% overall yield. The xanthone skeleton was formed by a one-step synthesis in 80% yield, and five of its novel derivatives were also obtained by this approach. This synthetic strategy and all the derivatives could be further used for the preparation of other natural xanthones. All the xanthones were characterized by NMR and ESI-MS, and the cytotoxicity of these xanthones was evaluated against HepG2 and HT-29 cells, and the preliminary structure-activity relationship was evaluated from the results. It was proved that the presence of 3-OH group in the molecule is crucial for its biological activity, while the presence of substituents at C-5 and C-6 may also be beneficial.